If you riot, social media will be used to track you down. That is no longer a surprise to anyone. A new twist in social media surveillance work following the London riots, though, may be the use of facial recognition technology to identify those involved.

After the riots in Vancouver earlier this year, following a Stanley Cup loss, a Canadian insurance corporation volunteered the use of its drivers' photos database should authorities wish to use facial recognition technology to identify and charge rioters. A spokesperson from the Vancouver Police Department tells me that the agency, while aware of the technology, ultimately decided not to use it.

"We are aware of the technology but have not used it in the investigation that is currently underway. We have many investigative avenues and tools that we are putting into use currently that are working well to advance the investigation," Constable Lindsey Houghton tells me.

Web vigilantes are doing their best to make sure facial recognition technology gets a fair shake in the London riots, though. Just last week, researchers established that off-the-shelf facial recognition technology mixed with Facebook's vast database of photos linked to people's real identities can lead to fairly reliable identification of complete strangers. Digital crime-fighters plan to use the same techniques the researchers used to identify students at Carnegie Mellon University to identify English rioters. On a Google group called London Riots Facial Recognition, a bunch of technophiles are discussing using Face.com's facial recognition API to create a Facebook app that will identify ne'er-do-wells in London.

After getting media attention, the Google Group members have made their group private, but here's a screenshot (above at right) of the members discussing the legal issues around identifying those involved...

As Jerry Brito notes at Techland, they're far from the only digital vigilantes (digilantes?) trying to identify law-breakers involved in rioting in London following the shooting of a 29-year-old man. (Note to Jimmy Wales: Judging from the number of vigilantes working for free on post-riot criminal identification, I suspect Wikipedia may be losing contributors because those who like to work for free on the Internet are starting to prefer digital superhero work to encyclopedia entries.) But this group's proposal to use facial recognition tools to do their work is a new twist in crowdsourced criminal identification. And it raises the question of whether London authorities, unlike Vancouver's, will harness the power of facial recognition technology in their investigations of the weekend's looting and rioting.